John Curl's Blowtorch preamplifier part III

Status
Not open for further replies.
Have you tried it? The digital file is not a vinyl rip made by a record company, this is a ridiculous idea.
I can assure-you that no one of those 2 files is a digital copy of a modern digital master mix.
Everything is blurry and froggy, drums are nowhere, no attack, distortion everywhere, no separation, no micro dynamic. It sounds like an 'ethnic' document of an old blues performance.
Ridiculous ? It happens more often that you seems to believe. And, if it is not a copy from a vinyl rip, and that, you will have to prove, it is a copy of a very old and damaged magnetic tape. Same than some of my 50 years old cassette tapes recorded during public performances at the mixing desk with a couple of microphones, that I was making at that time to evaluate the quality of my work.
What do I want for you or others? To check the files and show if you can find a difference in an ABX test.
As it it is like evaluating the sharpness of the lens from a photo out of focus at 25600 ISO, i did not even took care to copy those files in my server, updating the musical list etc. Too time consuming to demonstrate what ? That my ears are damaged by age ? I know-it well enough yet.
So i just listened 10 second of each on my pc speakers, and that was enough.
I have nothing against blind listening test of any audio gear, but they have to be correctly driven, beginning with an accurate choice of the source's qualities.
 
Last edited:
Member
Joined 2014
Paid Member
Partially, IMHO. What usually goes along with ADC sound quality is the quality of mics, effects processing, and the acoustical quality of the recording space. There are many small studios with small budgets now. Used to be a smaller number of big studios with bigger budgets. Studios use was time domain multiplexed, now everyone can have his own full time. The people operating the equipment are often much less well trained than before. In other words, pretty much everything has changed. All, IMHO of course.
I am really not sure how things were higher quality when the studios packed 5 or 6 different sessions in during the day. Not going to argue that the musicianship was there in the days that the wrecking crew were knocking out the backing for hit after hit one after the other, but the quality of equipment is much higher than it was even if some people still insist on a tubed Neumann for vocals.

Right now you have a potentially cleaner signal path than ever before. Now of course you and I differ in that I don't judge studio music as IMO its too mangled to meat quality targets. Accoustic music suffers from too many mikes in many cases and I do run screaming back to earlier recordings with minimal microphones.

As an aside I always enjoy reading John Atkinson's notes on his recordings as he gives a good insight into the decisions he made and why which are always informative.

But at the end of the day I will take the performance over the sound quality.
 
I think I have always get this in my systems since around 10 years ago when my amp was a special TDA2030A and my speaker was a transmission line with fourth order L-R. It was a revelation. I was designing the speaker, so the determinant factor is the speaker and as for the amp (quasi, 'darlington' LTP), it just didn't get in the way.

I would say that this is just an effect of tone correctness and resolution. <snip>

That all made much more sense to me than any measurement could.

Putting it all together with a basic understanding of preferred characteristics and then figure out which measurements are important to get there might be something to concentrate on, that’s basically what I’m trying to get a handle on here.......I don’t see how these qualities could sound ‘bad’ to anyone.

I believe phase is important and I put a lot of focus on it, I can hear the differences......especially in the feel or correctness (like you say) that’s why I have a hard time understanding when people who are supposedly trained professionals say it doesn’t matter.

I’ve always been critical of vocals when dialing a system in.

it’s funny you mention Adele....for some reason I can’t stand her either.
 
Member
Joined 2014
Paid Member
I can assure-you that no one of those 2 files is a digital copy of a modern digital master mix.
Everything is blurry and froggy, drums are nowhere, no attack, distortion everywhere, no separation, no micro dynamic. It sounds like an 'ethnic' document of an old blues performance.


So you can't tell them apart and you (as many usually do) chose to attack the source material rather than just admit it, or even suggest a differnt recording that meets your particular standards?
 
I can assure-you that no one of those 2 files is a digital copy of a modern digital master mix.
Everything is blurry and froggy, drums are nowhere, no attack, distortion everywhere, no separation, no micro dynamic. It sounds like an 'ethnic' document of an old blues performance.
Ridiculous ? It happens more often that you seems to believe. And, if it is not a copy from a vinyl rip, and that, you will have to prove, it is a copy of a very old and damaged magnetic tape. Same than some of my 50 years old cassette tapes recorded during public performances at the mixing desk with a couple of microphones, that I was making at that time to evaluate the quality of my work.

Thank you for your professional guess. It is this recording
Eric Clapton - I Still Do (Vinyl, LP, 45 RPM, Album) | Discogs
namely the Polydor Europe version. 45rpm vinyl.
Recorded at British Grove, UK.
Engineered by Glyn Johns and Martin Hollis
Mixed by Glyn Johns
Mastered by Bob Ludwig
Vinyl mastering by Bernie Grundman at BGM Mastering

So it goes, such are recordings nowadays. Please note I said not a word about sound quality.

Now the test files:
- one of them I made as a vinyl rip from this record myself
- the second one is the file issued by the producer that you may download if you buy the record. It is not a vinyl rip which you may easily find by file analysis at low frequencies - there is no vinyl surface noise added, but it has another issue at the high frequencies.

So, we have 2 very different files that can be seen in file analysis. It should be very easy then to get a positive ABX result, especially for those who can hear SOTA DAC differences, color of interconnect wires, resistor brands, capacitor brands.. Is it so easy or not?

P.S.: A guitar with a booster, like Clapton's, sounds distorted, such is life.
 
Last edited:
So you can't tell them apart and you (as many usually do) chose to attack the source material rather than just admit it, or even suggest a differnt recording that meets your particular standards?

In case of vinyl it is difficult to find similar or almost same digital download vs. vinyl rip (which can be made as a DIY by a moderately skilled person). And the vinyl condition must be good not to identify surface noise and cracks immediately. From my collection, this is the only choice that fulfills conditions. You know headphones are like a magnifying lens. No cracks or noises allowed for ABX ;)
However, signal differences between these 2 test files are quite huge so I would expect that a lightly trained ear should have a success in the ABX. Not necessarily the trained mouth or trained pen. These are different disciplines ;)
 
Member
Joined 2014
Paid Member
In case of vinyl it is difficult to find similar or almost same digital download vs. vinyl rip (which can be made as a DIY by a moderately skilled person). And the vinyl condition must be good not to identify surface noise and cracks immediately. From my collection, this is the only choice that fulfills conditions.
Absolutely agree. Interestingly Grove studios appears to cater for all perversions in recording and has everything from state of the art to early EMI mixing desks. The clapton album was recorded on multitrack analog tape according to this Prism Sound at British Grove | The Ear but with good DACs and great speakers apparantly sounds like 'liquid Mahogany' :)
All day, every day is a Jelly Roll day :)
Of course :)
 
Absolutely agree. Interestingly Grove studios appears to cater for all perversions in recording and has everything from state of the art to early EMI mixing desks. The clapton album was recorded on multitrack analog tape according to this Prism Sound at British Grove | The Ear but with good DACs and great speakers apparantly sounds like 'liquid Mahogany' :)

Of course :)

Hehe, liquid Mahogany :D. Now "names" again ;)
 
BTW, the Clapton's 2LP 45rpm sounds quite good. Of course it is better to listen to it through speakers than through headphones. The song I used, Alabama Woman Blues, has a booster guitar which is naturally distorted by the booster used. No distortion in piano keys. There are some tracks with acoustic guitars, however vinyl surface clicks did not allow me to use them for the test.
 
Somebody who knows a bit about designing DACs, John Westlake says
"Sonicaly I prefer low order noise-shapers with NO pole splitting, this impacts the noise floor at HF but I certainly cannot hear much above 15KHz, especially below 100dB! Low order noise shapers behaved well "dynamically" - especially during large changes of state... High order Noise shapers - especially with Pole splitting are just chaotic "Dogs" - sure everything looks nice with steady state sign waves, but stimulate the system with large changes of state and the output of each Noise-shaper "Node" can be seen to go nuts with wild excursions - then taking a long time to "Settle".

I still prefer the sound of the Philips SAA7350 noise sharper with all its MANY technical "warts" to any of todays ESS DAC"s.... and there is a HUGE margin in Sound quality.

This is an example of where a State of the art measuring DAC sounds worst then a "technically" inferior measuring DAC's - steady state test signal are not good at exposing such failings.

Also, systems with multiple internal feedback paths (such as Noise shapers) are good at hiding such ills - you need to develop tests that really expose such limitations.. and its not simple THD / SNR, some of these tests can only be analysed with access to each internal node of the feedback system monitoring the internal nodes response to transient events.

What I'm trying to say is that THD / SNR is not a sonic performance matrix with complex "digital" systems..."

Any comments from the people who claim well designed DACs measure well?
 
Last edited:
Somebody who knows a bit about designing DACs, John Westlake says

Any comments from the people who claim well designed DACs measure well?

Yes. John Westlake is a self taught designer who didn't received a formal university education and learnt electronics by observing his father's work. In general, self taught is ok, at least to start with; but to me is not good enough to land an ultimate expert status in any engineering domain. With the notable exception of high end audio, of course.

There's another thing that doesn't smell good to me; on his Wikipedia page it is stated black on white that he is now "preparing his Doctorate PhD research based on insight and understanding into an acoustic and system phenomenon observed over his career as an audio designer". If anybody knows a recognized University granting doctorates without graduating at Master level as a prerequisite, let me know.
 
Status
Not open for further replies.